Resin-impregnated water-resistant leather



Patented Apr. 14, 1 953 RE SIN -IMPREGNATED WATER-RE SISTAN T LEATHER Nicholas D. Cheronis, Chicago, 111., assignor of one-third to Edwin L. Gustus, Chicago, Ill.

No Drawing. Application October 26, 1948, Serial No. 56,663

. 1 j 1 This is a continuation-in-part application of my copending application Serial No. 613,009, filed August 27, 1945 (now abandoned). My invention relates to a new and novel leather and to .its preparation. More particularly, it relates to a method of making fibrous materials, and especially leather, water-resistant without harmfully afiecting its other characteristics, and to the leather or other fibrous material thus'produced. My method is particularly advantageous for leather, but may be used upon fabrics, webbing, and other fibrous products.

A specific object of my invention is to produce leather which is water-resistant, yet flexible, soft, tough, long-wearing and more resistant to heat andcold than are conventional treated leathers. Another object of my invention is the treatment of leather and other fibrous materials with novel aminosilane resins'described and claimed in my copending '(at' the time of filing my present application) applications Serial No. 616,475, filed September 14, 1945, and Serial No. 72,548, filed January 24, 1949. Application Serial No. 616,475 has been abandoned in favor of application $erial No. 72,548.

I Application Serial No. 72,548 has now matured into Patent No. 2,579,418, granted December 18, 1951.

A further object of my invention is to prepare solutions and dubbing which will impart waterresistant characteristics to leather or other fibrous material upon which used.

A stillfurther object of my invention is a method of treating leather so as to make it water-resistant without deleteriously afiecting the other properties of the leather which make it desirable for specific uses.

In the past, conventional water-proofing treatments for leather have been largely methods for filling the porous structure of the leather so as to render it impervious. Among the first of the methods was the old farm method of filling the leather with mutton suet. Since then other greases and waxes-have been used, largely with the same intent of coating the leather microscopically. At the same time, the leather so treated was rendered especially susceptible to heat and cold because the fiuidity or the grease and wax waschanged greatly with only a small change in, temperature. Boots treated with such grease were so stiff when cold that users would be forced to warm their boots in'order w fiut them on. The prior methods consisted largely of providing a grease or' other coating which rendered the leather water-resistant only be- 8 Claims. (Cl. 117-1355) cause the water could not penetrate the coating on the leather, and was effective only until the coating was fractured. My method on the contrary makes each fiber in itself more waterrepellent so that the water must penetrate'ea'ch individual fiber to affect that fiber, and as it does not form an impervious coat to exclude the water, the leather remains porous.

My method renders the leather water-resist ant, without rendering the leather impermeable; The degree may be varied by the quantity of compound used so that if desired, sufiicient can be added to, form a vapor-impermeable leather, but such is not ordinarily desired.

My invention provides a method of treating the leather so that the fibers themselves are water-resistant to such an extent that they repel water even when fiexed repeatedly, and the leather is soft and flexible to practically the same extent as the untreated leather, yet will resist the efiects of water to a far greater extent. My method will not waterproof leather to the extent that a sheet of rubber is waterproof, but will increase its resistance to water so that the leather will exhibit up to ten or more timesas much resistance on standard water-resistance tests as will the untreated leather, and .still remain Watervapor permeable.

The treatment is particularly useful for gloves and other leather articles in which water-resistance is at a premium, but in which the natural fiexibility and toughness of the leather must be retained. Any leather may be treated, and its water-resistance increased. The final properties of the leather will be largely those of the untreated leather except for the water-resistance, and accordingly, by a suitable initial choice of leather the treated leather may be used for any purpose for which leathers are desired.

Further, a dubbing prepared in accordance with my invention may be used for maintenance of my leather, and for the increasing of waterresistance and flexibility of conventional leather.

- By my invention, leather of any desired quality is treated with a solution or dispersion of certain aminosilane resins containing suitable modifiers, plasticizers and extenders, wherein the leather 1S im regnated with the resin at an intermediate stage of polymerization in which the resin is of low molecular weight and soluble in organic solvents. The solvent is removed by evapora' tion, and the polymerization of the resin is com pleted. The process possesses important diif'erences from known processes, because of poly merization is completed in the, final location rather than prior to treatment, and because of The monomer is not believed to be capable of existence in the free state. When n is 1, i. e., when n is one monovalent radical substituent on the silicon atom of the starting material, the resulting condensation product will thus be i. e., the atomic ratio between silicon and nitrogen will be 1: 1.5, the fractional number of nitrogen atoms being due to the sharing of the NHz group by adjacent cross-linked organosilicon groups.

Deamination occurs at comparatively moderate temperatures; consequently the completion of the polymerization in situ is non-injurious to the leather. Solutions and dispersions of the aminosilane resins and their mixtures with other resins in the incompletely polymerized state penetrate into the leather so as to give the desired qualities when polymerized. As a specific example, a suitable impregnant was prepared by heating, by weight, 15 parts of coumarone indene resin, having a melting oint of about 105-110 C., 20 parts of oil of oiticica, and 8 parts of linseed oil to a temperature of 200 C. for 15 minutes, then adding 20 parts of paraffin wax. Separately, a mixture was prepared of 10 parts tricresylphosphate, 6 parts iight paraffin oil, and 4 parts blown castor oil. Separately, 20 parts of styrene was heated to 135 C., 0.2 part of. benzoyl peroxide was added in small portions so as to keep the styrene near boiling as it polymerized The polymerization was allowed to continue until the viscosity increased to between 30 and 34 poises at 20 C. A solution was prepared of ethyl aminosilane res ns by allowing a solution of 117 grams of ethyl trichlorosilane (technical) in 200 grams of dry xylene to react with 200 m1. of liquid ammonia, filtering out the ammonium chloride, washing with 200 ml. of dry xylene and evaporating off the surplus'ammonia under vacuum. As prepared, the solution contained about 16% of the resin intermediate. A quantity of this solution containing 20 parts solids was mixed with the other three solutions. The resulting solution was diluted by the addition of xylene and mineral spirits so that the final concentration of solids was between 20-30%.

The solids content of the solution may vary from 5% to 30% depending on the add-on that is desired; for most purposes a content of 18 to 20% is used. Where it is intended to emulsify the resin solution prior to its application to leather, the solids concentration is preferably from 20 to 25% based on the weight of the emulsion; this is diluted in the mill to a preferred solids concentration of from 7 to 14%. The ratio of organoaminosilane resins to the rest of the. solids may vary between 10 to 90%, but it is particularly desirable that it range from 10 to 40% of the total solids; thus the organoaminosilane resin content of the solution may vary from 5% to 27%, and preferably from .5 to 12%.

If it is desired to store the solution for a period before use, an inhibitor may be used to slow down the rate of polymerization of the silicon-free polymerizable components of the solution. Volatile inhibitors, such as cyclohexylamine, benzylamine, n-butyl amine, tributyl amine, dicyclohexylamine, or aryl amines such as benzylamine, etc., may be used. An. amount of from 0.5% to 2% of the weight of the resins is usually satisfactory. When a non-volatile accelerator is present in one of the component monomers, it

may be left in the solution as the dilution in xylene usually arrests polymerization to an adequate degree.

A. deerskin glove leather was treated by dipping in the solution for 30-40 seconds, drying to evaporate the solvent and curing at 60-65 C. for 24 hours (or for 4 hours at 6065 C. followed by '24 hours at room temperature), during which time condensation and polymerization was completed. The weight of deposited solids ranges from 20-30% of the original weight of the leather.

During the impregnation with the resin, a .portion of the oil or fat which the leather contains was extracted .by the highly aromatic solvent used for the resins, and oil or fat should be replaced to keep the leather soft. Ordinary shoe dubbing is satisfactory, but a better one is prepared by including .such highly water-repellent components as 5% octadecylamine and about 51% silicon amine resin which has been previously polymerized. For example, the dubbing may consist of:

Parts Beef tallow 20-40 Animal oil 20-30 Amorphous mineral wax' 8-10 Silicon amine resin 10-30 Octadecylamine 5-10 Aluminum stearate l- 2 The solution to be used in the treatment of the leather comprises an aminosilane compound obtained from the ammonolysis of organosilicon halides, either pure or mixed, where the degree of halogenation is sumciently high togive polymerizable compounds; at least two valences of the silicon must be substituted by halogen atoms in order that polymerized aminosilanes may be obtained. Such compounds are methyl trichlorosilane, dimethyl dichlorosilane, ethyl trichlorosilane, diethyl dichlorosilane', methyl ethyl dichlorosilane, phenyl trichlorosilane, diphenyl dichlorosilane, phenyl methyl dich-lorosi-lane, ethyl trfiuorosilane, ethyl triiodosi-lane, etc. The term ammonolysis includes reactions with not only ammonia, but also with substituted ammonia, such as the primary amines, methyl amine, butyl amine, isobutyl amine, phenylamine, hexamethylene diamine, ethylene diand polyamines, etc. It ispossible that during the final polymerization step in situ nitrogen of the amino groups of the resinous product form secondary linkages with the protein fibers and thus serve as anchorages for the resin. The resulting resinous products are characterized by a silicon to nitrogen ratio of from 1:1 (approximately) to 1:15 (approximately) they are further characterized by repeating units of silicon linked to nitrogen as an integral. part of the polymer chain in which the repeating units consist of. silicon substituted by monovalent hydrocarbon radicals, as is more fully explained in my copending application 616,475. Other components of the solution comprise one or more of the following: (a).

aeaaooa resins already preformed (completely polymerized) as coumar resin, ester gum, rosin, rosin modified phenolic, maleic-resin, (b) unsaturated glycerides of the type of China-wood oil, oil of oiticica, perilla, linseed etc., partially polymer-r.

ized by heating to a certain viscosity, (c) plasticizers such as dibutyl phthalate, tricresyl phosphate, etc., (cl) a partially polymerized resinforming material, such as styrene, coumar, coumarone indene, modified Bakelite, etc.

A particularly preferred solvent consists of a mixture of xylene and mineral spirits in the ratio of about 4:1. Other suitable solvents are xylene, toluene, benzene (to be used with caution because of the toxicity of its vapors), highboiling point ethers such as butyl ether, Stoddard solvent; amyl or butyl alcohol in suitable amounts say ,10%, may be added to the inert solvents. Other suitable solvents which are non-settling, economical, and non-reactive with the aminosilane resin will readily occur to the expert in the art in the light of the foregoing disclosure.

The organoaminosilane resins may be used either alone, or in conjunction with other resinous water-repellent materials to treat leather. If they are used alone, the type of aminosilane resin must be selected so that when it, is cured it will yield a soft flexible non-tacky resin. This can be accomplished by increasing the ratio of iii-functional monomer and decreasing the ratio of the tri-functional monomer in the mixture which is to be ammonolyzed. For example, if the mixture ammonolyzed consists of 95% trihalosilane (RSiCla) and 5% dihalosilane (RzSiClz) the resulting resin will have a considerable number of cross links between relatively short chains and hence will have a tendency to brittleness and granulation under dynamic conditions. On the other hand, if the mixture ammonolyzed cons'ists of 80% or 70% or,60% or 50% tri-functional, and 20% or 30% or 40% or 50% di-functional the resulting resins will have a tendency toward softness and flexibility. On the other hand, as the amount of the di-functional monomer is increased the ease at which the resins cure at room temperature by evolution of ammonia decreases. In other words, it will require heat to effect curing. However, it is clear that by controlling the ratio of the tri-functional and difunctional halosilanes of the ammonolyzed mixture, it is possible to obtain a series of resins which after curing will vary all the way from the oily type to the hard brittle type. The part'icular type of resin to be used depends on the ultimate use. If the leather to be treated is sole leather, a hard, tough and slightly resilient resin' must be used since the flexing is at a minimum. On the other hand for glove leather, a soft nontacky resilient resin is required.

It has been found out by actual experimenta tion that the amount of aminosilane resin to be introduced into leather need notv be very high;;

For example, inorder to obtain leather-of high degree of water repellency, it is necessary first to coat the fibers and fiber-bundles which make up the leather so as to stop their wicking action; at the same time, however. the interfiber spaces must be filled so as to reduce the empty or void spaces and therefore reduce the amount of water which will tend to be forced by pressure under flexing into the leather pores or empty spaces. The silicon resins .are ideal for coating theflbers and fiber bundles so-as to impart ahigh degree of water repellency. Although it is pOSSi-f: ble to coat the fibers in the interior of the leatherwith silicon resins alone, the cost of such a process is likely to be rather high because of the present price of silicon resins; therefore it is (a) they should not react with the aminosilane.

resins before the curing period; (b) they should be compatible with the aminosilane resins after curing; in other words they should not separate as a separate film after curing, but should form either a solid solution or a compound with the silicon resin; (0) they should have a comparatively low molecular weight prior to curing, so

that they can be introduced in the same way asthe aminosilane resins, and they should be capable of further polymerizationafter deposition in the same manner as the aminosilane resins.

Certain polymeric substances fulfill these requirements. They are madefrom monomers and are incompletely polymerized, that is, they are polymerized until they form liquid low molecular weight polymers capable of still further polymerization; the polymerization is then arrested, e. g. by the use of a suitable inhibitor. examples of which are set forth above. Under these conditions of preparation, these partial polymers have the following characteristics: (a) they are liquid at room temperatures of viscosity of 3-60 poises; (b) are soluble in a variety of organic solvents; (c) arestable and can be stored for long periods of time; (d) are capable after deposition and evaporation of the solvent and inhibitor to polymerize further and thus form an anchored film, that is, a film firmly bonded to the impregnated base.

For the preparation of the partial polymer Which can be used in conjunction withthe aminosilane resins, the following monomers have been used either alone or in mixtures: methyl acrylate,' ethyl acrylate, butyl acrylate, oct-yl acrylate and lauryl acrylate; methyl methacrylate, butyl methacrylate, lauryl methacrylate; chlorostyrene, vinyl acetate, vinylidene chloride.

Another type of polymerizable film that can, be used in conjunction with the aminosilane" resins is a film produced by polymerization of a mixture of oxidizable unsaturated glycerides or drying oils and resins. For example a mixture of oils of oiticica, China-wood, and linseed oil heated with a coumarone indene resin or phenolformaldehyde resin is an example of this type of polymerizable film; resins are heated to about 200 C. until the required degree of polymerization of the unsaturated'glycerides has taken place and then are allowed to cool to room temperature when they can be mixed with the aminosilane resin, or mixture of aminosilane resin and partial polymeric.

material.

No matter what the compositionof the resin is, it should be plasticized in order that the required degree of the flexibility is obtained.- The nature of the plasticizer mustbe such that it is compatible and :non-reactive with; the .amino-..

Therefore if the silicon resinstyrene;

Equal parts of oils andthose useful-for this purpose are: esters-of phosphoric' acid, such ascresyl" phosphates, butyl phosphates: esters? of: phthalic acid,. such as butyl phthalate. octyl phthalates: and? the like;

esters of glyceroliandglycol; oilssuch as-castor: oil and neats-foot 011; low melting" point' paraffin wax (M. E. 60 65 0.). r The amount of -plasticizer to "be used depends: on the type ofleather treated; Generally-theamountnof plasticizing is minimum in sole leather treatment-and maximum-in gloveleather'treatment;

Once the nature of the composition of the'mix ture'to-be introduced into leather. has beenm'ade;

achoice must be'made as to themethodof introduction. Generally: there. are two methods (a) non-aqueoussolution method; (bl-aqueous emulsion method. In 'the -non-aqueous solution method, the aminosilane together with any other film producingsubstancesor mixture of'substances such as partial polymers, resin-oxidizabletoil mixture andthe like,v are dissolved into an organic solvent-such as xylene, toluene, or mixturesof xylene,- aliphatic naphtha, and alcohols; The-strength-of the solution is adjusted-depending on the-deposition required. For example, if a.25-30% deposition. of solids by weight of leather is :required the solution should contain 40'%-ofsolids.- On. the other hand if only a-- deposition1is required, a solution isadequatee Theleather'may be treated by dipping, sponging; orspraying; Inany case theexcess of the solution'is drained or removed by -centrifuging and the skin is placed in a-dryerfor removal of "the solvent and curing. The tem perature required .is 110 to 140 F. or -65 C.

During-the first hours-of-the: heating the solvent and inhibitors evaporate and the polymerization in situ begins. curing-' varies with the nature ofthe aminosilane resin used, the'nature of the"partial polymers. If'no oxidizable-oil-resin mixture'has been used, the curing is substantially complete within 4 hours; if the amount of di-functional monomers in theaminosilane resin is high, the curing will take longer; if oxidizableoil-resin mixture has beenused; the skin is allowed to stand at room temperature for 48 hours after the initial heating when the oxidizable'phase'is complete; Thecuring in'the case of the aminosilane resins which .have high ratio'of tri-functional monomers can becompleted speedily within .a few minutes. at 90" C. or slowly at room temperature In theaqueous. emulsion method',,the amino-- lanexesinor: aminosilane resin mixed with.

partial. polymeric. resins are dissolved in a watereinsoluble organic solvent, of. the hydrocarbon type such as xylene, toluene and, the

like; Small amounts. of alcohol, ethers, ke-

tones, may be: used' but; not ztoiexceed; 10-15%' of- 'the total. amount-'ofwthesolvent used since emulsification becomes. dimcult' if i appreciable amounts of; polar solvents; are-present; The.

The time required for complete amountof solvent i used: is: preferably-L ad'- justed "so that'the solvent content in the final emulsion is 25-40%. The presence-oi thesolvent is necessary for the success of .this process and although it is possible to emulsify the"resin'-- oil mixture without the presence of the solvent the-resultant emulsion deposits most of the resins on the surfaceandxouter layers of the leather, instead of penetrating the interfiber'space of the leather and uniformlydistributing the deposited After the liquid aminosilane resins and other.

partial polymers are dissolved then theyare emulsified by special types of emulsifying agents which give a dispersion or emulsion having the desired characteristics which are: (a) the emul-' sion should not be so unstable that itbreaks sud denlywhen' it "is brought incontact'with the skin;- thus depositing" the" resinous I materials on the outer surface of the leather; (b) on the other hand, the emulsion should not be so excessively stable so that it will" require several hours of tumbling it'with the skin'in' the leather mill so that it may break, for-in such case'the leather is damaged by too much tumbling; (c) the emul sion should break within 15-45 minutesafter coming in contact with the wet skin, and insobreaking the emulsified particle should slip. between the fiber-bundles within the leather and there be discharged depositing the organic particle in exchange with water; In other words, the wet skin gives up water in exchange-for organic particles. The'organic particles consist of droplets of solvent containing resins; as the solvent evaporates (and the. evaporation starts within the mill since the temperature during the operation is about to F.) the deposition of thefilm takes place. This deposition is more uniform and more penetrating than treatment with a. solvent; After the skin has been'treated with the emulsion then it is placed into'a room heated to 120-l30 F. and allowed; to stay 24' to 48 hours. During this time the'waterevaporates and the polymerization or curing is completed.

Further detailsof leather treatment by'contact.

with an emulsion containing asolution of silicon amineresinare set forth in my copending appli cation Serial No.. 643,493, filed January 25, 1946.

Each method of introduction has some. ad-

For example,

whichhave been already manufactured the solvent method is used. On the other hand, the emulsion, method is better adaptable to large scale'tannery operation, since it removes the hazard. dueto flammable solvents andleadsto a. more uniform. deposition and at the. same .time It.

cessfully with. the emulsionmethod; on theotherhand, an aminosilane resin derived:from the ammonolysis of phenyltrihalosilane and diphenyldihalosilane undergoes very little hydrolysis: overthe period of time required for emulsion operation, and hence it can be. used,

with the emulsion method. Such aminosilanes that'are subject to rapid hydrolysis can be used successfully, by .the non=aqueous solvent method;

The following examples illustrate some of the principles discussed in the preceding paragraphs:

' Heat to 125 C. and add slowly over a period of -1-5v minutes 0.5 part of benzoyl peroxide and -continue heating until the viscosity of the liquid ,intermediate polymer is to poises at 25 C. vNow add 0.1part of cyclohexylamine as inhibitor and dilute with xylene or toluene to 200 grams thus obtaining a stable solution. Cool to room temperature and add:-

Aminosilane resin, 30 parts (from the ammonolysis of a mixture of 60 parts of ethyltrichlorosilane and 40 parts of diethyldichlorosilane) Octyl phthalate (plasticizer), 14 parts Solvent sufiicient to make up a solution which has 25% solids.

FORMULA B Aminosilane resin with partial polymers Parts Styrene monomer 10 Vinyl acetate 10 Methyl methacrylate 10 Butyl acrylate 30 Benzoyl peroxide 0.8

Polymerize to 12-15 poises Viscosity and add:

Cyclohexylamine 0.2 Paraffin wax 10 'Iri'cresyl phosphate 10 Aminosilane resin The aminosilane resin was produced from the ammonolysis of 80 parts of phenyltrichlorosilane and 20 parts of diphenyldichlorosilane, as set forth in Example 8 of my copending application Serial No. 72,548 (which example is in turn based on Example 6 of my application Serial No. 56,662,

filed. October 26, 1948, and now abandoned in favor of my application No. 72,548.) For an example of a treatment by the solution method enough xylene is added to give a solution. For an example of a treatment by the aqueous emulsion method the 100 parts of the mixture are dissolved into 180 parts of xylene and then 5 parts of sulfated neats-foot oil and 5 parts of a'commercial emulsifier such as a sodium salt of a higher synthetic alcohol sulfate, known by the trade nameof Tergitol, e. g. (Tergitol Peneftrant 4 which is the sodium salt of 7-ethyl-2- methyl-undecanol-l-sulfate) are added and then emulsified by mixing with 220 parts of water and passing through a colloid mill. About 500 parts of emulsion are obtained containing 20% of solids and having a pH of 9.2 to 9.5. Such emulsion should be used immediately after preparation.

For use it is diluted with an equal amount of Water heated to 50 C. and then added to the .leather mill containing the wet skin. Exhaustion is subsantially complete within -45 minutes.

The spent liquor is substantially free of any polymer thus showing complete absorption. '75

:Partial polymeric resin 15 *Oxidiz'able oil-resinmixture; 35 parts Plasticizing mixture, 10 parts responds .to 54.61% of hide substance.

EXAMPLEC Aminosilane resin with partial polymers and oxidizable oils Aminosilane resin, 20 parts (Obtained by the ammonolysis of '70 parts of phenyltrichlorosilane and 30parts dimethyl- .dichlorosilane) mixture, 35 parts Composition: butyl' methacrylate 15 parts, styrene 10 parts, vinyl acetate 10 parts, benzoyl peroxide 0.15 part; polymerized to 10-12 poises viscosity and inhibited with 0.05 part cycloh xylami Composition: Indenecoumarone resin 15 parts;

.' oil of oiticica' 14 parts, linseed oil 3 parts, heated to 200 C. for 20 minutes and then cooled to C. and mixed with 3. parts of paraffin ,wax and 0.1 part of 6% cobalt naphthenate (drier) Composition: castor oil 3 parts, tricresyl phosphate 3 parts, and octyl phthalate 4 parts.

- EXAMPLEi- A piece of upper leather weighing 810 grams gave on analysis 8.61% of nitrogen which cor- The grease content was 22%. This piece of leather was treated with solution of Formula A and after curing it was found to weigh 1014 grams, a gain of 25.2%. Onthatbasis of gain if there had been no nitrogen introduced the percentage of nitrogenin the leather would be about 6.9%. However, on analysis the leathergave 7.65%, a gain of 0.75%.. In addition, the leather contains silicon as shown by analysis for silica in the ash. The amount of silica found was 1.7%.

EXAMPLE 2 Treatment of a hide by the emulsion method. A hor'sehide was used weighing 960' grams'coritaining 11% of grease. The hide was first chrome-tanned and then fat-liquored so that Both the water and the emulsion were heated to 60 C. before addition. The wet skin was added and tumbled for 50 minutes. The pH of the spent liquor was 6.2. The skin was removed and placed in the hot room -120 F.) for 48 hours and then staked as usual. The dry skin weighed 1245 grams, a gain of 29.5%. The analysis for nitrogen before and after showed an increase in the nitrogen content by 0.54%. i

The degree of water-resistance of the leather depends upon the type and amount of resins used.

Normally the water vapor permeability of the leather should not be drastically reduced. The

:11 upper limit of solids'ffromfresin dispersion, including theplasticizer, modifier, softeners, etc., is around 30-40'by weight based'upon the untreated weight of'the leather. However, where permeability is not important, ,as .in.leather straps,belts, etc.,- the leather can be impregnated 'to.50%'solids or more advantageously. LLInfgloves, from 15-30% by weight is a desirable range. However, the value .oithelresin treatment varies with .the .amount ,of solids,. and; is uite; marked .evenwhen as low as1f5j%I.is.,deposited. ,Aihig'her percentage of aminosilane resin particularly of Lleathers, ,it. is .desirablehas undue heating. can

become harmful to the leather. I'I'he .deamination polymerization of amino'silane resins'jtakes place at lower temperatures than thedehydration polymerization of silicone resins, due to the low boilingpoint of ammonia; this property is therefore particularly desirable in the ap- 'plication ofaminosilane resins to leather.

Thus the amount of --:solids deposited in the leather from a resin solution, ranges fromI-about %.to 50% basedon theltotal weightlaftertreat- -ment; for most practical purposes .I .prefer l0%-30%. The amount of organosilicon amine resin add on in the leather. accordingly ranges from .5% to 45%.

"The amount of .solids deposited in the leather by vemulsion treatment ranges: from about to 45% based on the weight of the impregnated leather; a highly desirable leather is obtained with a solids -depositionoi about to;4'0% from an. emulsion.

'l'I'he Si content of leather treated with :the organosiliconamine resin solution or emulsion maybe as little. as 2% of the "Si content, untreatedlleather being.';04%. "By saturating-the leather with aconcentration of 45% silicon amine resin intermediate, '1 havesuccee'ded; in raising the Si content of heavy duty leather'to" 11.5%. However, for mostnpractical purposes, I have 'found aSi analysis- 011.4% to 2.3% .to besufli- .lcient to. impart the desired water-res-istanceland suppleness to the. leather.

'Ihev degree of partial :polymerization1before ..,impregnation can be determined by viscosity tests or by Vcryoscopicaaverage; molecular weight ..determination; the organosilicon amine .resin 'cintermediates, in-theirpartially.polymerizedstate "tween 3 and 12 poise -and.especiallythose between 4 and 8 poises.

Molecular weights of the organosilicon amine resin intermediates maybe upto 5000, depending on the molecular weight *of'the monomer; their average molecular weight usually varies from 1250 to 1600, and,.in my;..pre-

:ferred' range, it isbetweenAOO and'800.

I claim:

1. In a method-of imparting"water-resistance .stoanair-permeable fibrous material, the steps "which comprise: impregnating .said fibrous matei'rial with a solution, 'aninert volatile organic fIhe ,aminosilane resins ;permit ,the l ::solvent, :of an incompletely rpclymerized .aliquid silicon amine resin characterized :;by :repeating units of silicon linked to nitrogen as an integral part of the polymerchain which the repeating units consist of silicon substituted by from one to two monovalent hydrocarbon radicals, said silicon being attached to nitrogen substituted by amember of the group consisting of hydrogen and hydrocarbon radicals, at least "half "of '-:said "repeating units beingsubstitute'd by'only one-of saidmonovalenthydrocarbon'radicals per-silicon atom, said silicon amine resin being polymerized to a liquid capable of further'polymerization to a solid and having in the free state a viscosity of from about'3 to-zaboutfiil poises measuredsat-ZO" "C., the amount of'dissolved -is'ilicon amineresin deposited in said'iibrous material being'between about 15% and about of the "weightof said "fibrous material; and further-polymerizing said resin in the 'interfiberspace' of said "fibrous material at a "temperature not exceeding'about 90 C. to form a solid coating of said silicon amine resin on the individual fibers of said fibrous material-so as to make said'fibrous' materialwater- 're'sistant without destroying its air-permeability.

2. In a method of imparting water-resistance to an air-permeable fibrous material, thesteps which comprise: impregnating said "fibrous material with a solution, in an inert-"volatile organic solvent, of an incompletely polymerized liquid silicon amine resin characterized by repeating units of .silicon linked to nitrogen as an integralpart 'of the "polymer chain in which the repeating units consists of silicon substituted by one monovalent hydrocarbon radical, said silicon being attached tonitrogen substitutedby a member of the group consistingv of hydrogen and hydrocarbon radicals, said silicon amineiresin being polymeriedto a'liquid capable'oi'further polymerization to a solid andhaving in the free state a viscosity of from about;3 to. aboutBOpoises measured at"20'C., the amount of dissolved silicon amine resin deposited in said fibrous. material being between about 15% andabout 45% of the weight of said fibrous material; and further polymerizing said resin in :the' .interfiber =space of said fibrous "material at a temperature ,not

exceeding about Cxto'forrn a solid-coating of saidsilicon amine resinon the individual fibers of saidfibrousmaterial so asto make .saidi fibrous material water-resistant without destroying its air-permeability, said further polymerized :sil-

icon ,amine resin Shaving 1 an :average :ratio :of .i1

atom .of'silicon to approximately 11.5 .atoms of nitrogen in. itsfirepeatingunits.

3. Ina method of imparting water-resistance to leather,ithe"steps which comprise: impregnating' said leather with an aqueous :emulsion-oi a solution,in an inert volatile organic solvent, .of

Jan incompletely polymerized liquid silicon amine resin characterized xby 'repeating units of silicon linked to nitrogen; asan integral part :of'the-poly- -merchain in whichthe repeating units consist of silicon substituted byirom one to two monovalent hydrocarbonradicals, said 'siliconbeingattached to nitrogen substituted bya member of the group consisting-of hydrogen and hydrocarbon radicals, at least half of said repeating units dissolved silicon amine resin deposited in said leather being between about .5% and about 45% of the weight of saidileather; breaking said emulsion inside said leather; and further polymerizing said resin in the interfiber space of said fibrous material at a temperature not exceeding about 90 C. to form a solid coating of said silicon amine resin on the individual fibers of said leather so as to make said leather Water-resistant without destroying its air-permeability.

4. The method according to claim 3, wherein said emulsion is broken inside the leather by tumbling said leather.

5. A water-resistant air-permeable fibrous material whose individual fibers carry a solid coating of a silicon amine polymeric resin characterized by repeating units of silicon linked to nitrogen as an integral part of the polymer chain in which the repeating units consist of silicon substituted by from one to two monovalent hydrocarbon radicals, said silicon being attached to nitrogen substituted by a member of the group consisting of hydrogen and hydrocarbon radicals, at least half of said repeating units having only one said monovalent hydrocarbon radical substituent per silicon atom, said coating being formed on said individual fibers by the method of claim 1.

6. A composition for imparting water-resistance to fibrous materials comprising a solution in a common inert volatile organic solvent, of an incompletely polymerized liquid silicon amine resin characterized by repeating units of silicon linked to nitrogen as an integral part of the polymer chain in which the repeating units consist of silicon substituted by from one to two monovalent hydrocarbon radicals, said silicon being attached to nitrogen substituted by a member of the group consisting of hydrogen and hydrocarbon radicals, at least half of said repeating units being substituted by only one of said monovalent hydrocarbon radicals per silicon atom, said silicon amine resin being polymerized to a liquid capable of further polymerization to a solid and having in the free state a viscosity of from about 3 to about 60 poises measured at 20 C., and of an incompletely polymerized organic-solvent-soluble liquid polymer of a member of the group consisting of alkyl acrylate, alkyl methacrylate, s t y r e n e, chlorostyrene, vinyl acetate, and vinylidene chloride, and capable of further polymerization to a solid; the proportion of said silicon amine resin being between 10% and of the total amount of polymers in said composition.

7. A leather treating composition according to claim 6, wherein the proportion of said silicon resin is between 10% and 40% of the total amount of polymers in said composition.

8. A leather-treating composition comprising in a common inert volatile organic solvent: an incompletely polymerized liquid copolymer of styrene and. of a member of the group consisting of alkyl acrylate and alkyl methacrylate, and an incompletely polymerized silicon amine resin characterized by repeating units of silicon linked to nitrogen as an integral part of the polymer chain in which the repeating units consist of silicon substituted by from one to two monovalent hydrocarbon radicals, said silicon being attached to nitrogen substituted by a member of the group consisting of hydrogen and hydrocarbon radicals, at least half of said repeating units being substituted by only one of said monovalent hydrocarbon radicals per silicon atom, said silicon amine resin being polymerized to a liquid capable of further polymerization to a solid and having in the free state a viscosity of from about 3 to about 60 poises measured at 20 0.; the proportion of said silicon amine resin being between 10% and 90% of the total amount of polymers in saidcomposition.

NICHOLAS D. CHERONIS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,952,137 Muller Mar. 27, 1934 2,258,220 Rochow Oct. 7, 1941 2,280,830 Johnson Apr. 28, 1942 2,306,222 Patnode Dec. 22, 1942 2,356,879 Pense et al Aug. 29, 1944 2,364,692 Cassel Dec. 12, 1944 2,377,689 Hyde June 5, 1945 2,385,800 Douty et a1. Oct. 2, 1945 2,392,805 Biefeld Jan. 15, 1946 2,462,635 Haber Feb. 22, 1949 2,553,314 Haber May 15, 1951 FOREIGN PATENTS Number Country Date 915,190 France July 16, 1946 

1. IN A METHOD OF IMPARTING WATER-RESISTANCE TO AN AIR-PERMEABLE FIBROUS MATERIAL, THE STEPS WHICH COMPRISE: IMPREGNATING SAID FIBROUS MATERIAL WITH A SOLUTION, IN AN INERT VOLATILE ORGANIC SOLVENT, OF AN INCOMPLETELY POLYMERIZED LIQUID SILICON AMINE RESIN CHARACTERIZED BY REPEATING UNITS OF SILICON LINKED TO NITROGEN AS AN INTEGRAL PART OF THE POLYMER CHAIN IN WHICH THE REPEATING UNITS CONSIST OF SILICON SUBSTITUTED BY FROM ONE TO TWO MONOVALENT HYDROCARBON RADICALS, SAID SILICON BEING ATTACHED TO NITROGEN SUBSTITUTED BY A MEMBER OF THE GROUP CONSISTING OF HYDROGEN AND HYDROCARBON RADICALS, AT LEAST HALF OF SAID REPEATING UNITS BEING SUBSTITUTED BY ONLY ONE OF SAID MONOVALENT HYDROCARBON RADICALS PER SILICON ATOM, SAID SILICON AMINE RESIN BEING POLYMERIZED TO A LIQUID CAPABLE FURTHER POLYMERIZATION TO A SOLID AND HAVING IN THE FREE STATE A VISCOSITY OF FROM ABOUT 3 TO ABOUT 60 POISES MEASURED AT 20* C., THE AMOUNT OF DISSOLVED SILICON AMINE RESIN DEPOSITED IN SAID FIBROUS MATERIAL BEING BETWEEN ABOUT .5% AND ABOUT 45% OF THE WEIGHT OF SAID FIBROUS MATERIAL; AND FURTHER POLYMERIZING SAID RESIN IN THE INTERFIBER SPACE OF SAID FIBROUS MATERIAL AT A TEMPERATURE NOT EXCEEDING ABOUT 90* C. TO FORM A SOLID COATING OF SAID SILICON AMINE RESIN ON THE INDIVIDUAL FIBERS OF SAID FIBROUS MATERIAL SO AS TO MAKE SAID FIBROUS MATERIAL WATERRESISTANT WITHOUT DESTROYING ITS AIR-PERMEABILITY. 